1. Field of the Invention
The present invention generally relates to storage apparatuses and computer-readable storage media, and more particularly to a storage apparatus that carries out a write verify process in which information is written on a recording medium and an inspection is made immediately thereafter to verify whether or not the information was written correctly, and to a computer-readable storage medium which stores a program for causing a computer to carry out such a write verify process.
2. Description of the Related Art
In the case of a magneto-optical disk drive, for example, the laser power condition required to write information on and to read information from a magneto-optical disk is set to a value that is set in advance or determined by a test write. A verify process is carried out immediately after writing information on the magneto-optical disk under the set laser power condition, so as to verify whether or not the information was written correctly. If the information is not written correctly and cannot be verified, the write and/or read conditions are changed and a retry process is carried out up to a predetermined number of times. If the information cannot be verified even after the retry process is carried out the predetermined number of times, it is judged that a sector of the magneto-optical disk to which the information is written is a defective sector, and an alternate process is carried out to skip to an alternate area on the magneto-optical disk.
When carrying out the retry process, the laser power is varied and the magnetic field condition is varied in some cases, in order to cope with the inconsistency in the test write operation, the change in the environment condition such as the temperature, the inconsistency in the test write operation caused by the combination of the magneto-optical disk drive and the magneto-optical disk, and the shift in the sensitivity of the magneto-optical disk. Particularly due to the recent considerable increase in the recording density, there is a tendency for the tolerable error from the optimum write laser power, that is, the power margin, to decrease. But since the power margin is greatly affected by the inconsistencies described above, it is not possible to simply reduce the number of times the retry process is carried out.
In the case where minute defects that could not be registered by a media manufacturer as initial defects exist on the recording medium or, foreign particles such as dust particles adhere on the recording medium after the defect registration, the write verify process as a whole requires an extremely long processing time, because the alternate process is carried out after carrying out the retry process with respect to all of the specified plurality of tracks on the recording medium. For this reason, in some cases, a command time-out may occur in a host unit or, a freezing of an operation screen may occur in the host unit. Particularly when a write cache of the storage apparatus is valid and continuous data are written in one operation, a command process spanning several tens of tracks is generated, and there was a problem in that the probability of the time-out or freezing occurring becomes high, because of the time required to carry out the retry process and the alternate process.
In addition, when the retry process is carried out a large number of times, the writing is made with respect to the sector on the recording medium where the read success rate is low. Consequently, there was a problem in that the a read error may be generated, when the environment condition of the storage apparatus is later changed or, the information is later read from this recording medium by another storage apparatus.
The problems described above are not limited to the magneto-optical disk drive, and similar problems were also encountered in storage apparatuses that are designed to carry out the write verify process with respect to a recording medium such as an optical disk and a magnetic disk.